1. Field of the Invention
This invention is in the field of blade folders.
2. Description of the Prior Art
Compressed air has been utilized in various folding apparatus in the past, such as is shown in several prior art patents disclosing the use of compressed air jets to force a central portion of a sheet of material between a pair of pinch rollers for effecting a fold. Essentially, these devices have utilized the compressed air instead of a folding blade or knife as is used for folding in the presently described embodiment.
U.S. Pat. No. 3,506,255 to Jahn et al shows the use of air flow for both page flattening and page lifting in a cross-fold rotary machine. The folding operation is different from that in the presently disclosed quarter folder apparatus and additionally the nozzles are mounted away from the folding blade either on the machine frame itself or on a "blank holder". The air jets of Jahn et al are not maintaining the alignment and flatness of a group of pages having free ends nor is the action of the sheet being folded of the same type as in a quarter folder apparatus wherein proper maintanence of the page array is critical to avoid undesired folding and dog-eared edges.